Preparation method and application of two-dimensional BiOBr composite attapulgite photocatalyst

Abstract

The invention discloses a preparation method and application of a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst, and the preparation method comprises the following steps: calcining attapulgite, grinding, stirring with an HCl solution, centrifugally washing to be neutral, and drying to obtain acidized attapulgite; the preparation method comprises the following steps: dispersing acidized attapulgite in glycerol, performing ultrasonic treatment, and adding bismuth nitrate pentahydrate to obtain a solution A; dissolving hexadecyl trimethyl ammonium bromide in glycerol to obtain a solution B; dropwise adding the solution B into the solution A, uniformly mixing, transferring to a high-pressure reaction kettle for reaction, cooling, washing and drying to obtain a black precursor; dispersing the precursor in deionized water, stirring, centrifugally washing and drying to obtain a Bi4O5Br2 / attapulgite composite photocatalyst; the photocatalyst with a'sheet-rod 'composite structure is prepared by pretreating attapulgite and combining a solvothermal method and a hydrolysis reaction, so that the degradation efficiency of antibiotics in a water body is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of composite catalyst technology, specifically relating to a method for preparing and applying a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst. Background Technology

[0002] Antibiotics, due to their complex structure and persistent toxicity, are difficult to remove completely using traditional water treatment processes and have become a new type of environmental pollutant of global concern. In recent years, my country's "List of Key Controlled New Pollutants" has included antibiotics as a key control category, highlighting the urgent need to develop efficient and green removal technologies.

[0003] Photocatalysis technology achieves the complete mineralization of organic pollutants by generating highly reactive oxidizing radicals, offering advantages such as mild reaction conditions and no secondary pollution. Bismuth-based halide oxides (such as BiOBr and Bi4O5Br2) have become a research hotspot in the field of photocatalysis due to their suitable band gap and visible light response characteristics. However, pure Bi4O5Br2 suffers from problems such as high recombination rates of photogenerated electron-hole pairs and difficulties in recovery. Furthermore, existing Bi4O5Br2 photocatalysts exhibit low activity, poor stability, and insufficient antibiotic removal efficiency, limiting their practical application.

[0004] Attapulgite (ATP), a layered chain silicate mineral, is characterized by its large specific surface area, strong adsorption capacity, abundant sources, and low cost, and is often used as a carrier for modified photocatalysts. Studies have shown that combining bismuth-based semiconductors with attapulgite can leverage the adsorption properties of attapulgite to enrich pollutants and promote the separation of photogenerated carriers through interfacial interactions, thereby synergistically improving photocatalytic efficiency.

[0005] In existing technologies, the preparation of bismuth-based composite materials mostly employs simple mixing or co-precipitation methods, which suffer from problems such as weak interfacial bonding and poor dispersibility. Therefore, developing a Bi4O5Br2 / attapulgite composite material with tight interfacial bonding, high photocatalytic activity, and excellent stability is of great significance for promoting the development of antibiotic pollution control technologies. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing and applying a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst, thereby solving the above-mentioned technical problems existing in the prior art.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for preparing a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst includes the following steps:

[0009] S1. Attapulgite pretreatment: Attapulgite was calcined at 400℃ for 2h, ground, stirred with 3mol / L HCl solution for 3h, centrifuged and washed until neutral, and dried at 60℃ for 8h to obtain acid-treated attapulgite.

[0010] S2. Precursor preparation: Acidified attapulgite was dispersed in glycerol and sonicated for 1 h. Bismuth nitrate pentahydrate was added to obtain solution A. Separately, hexadecyltrimethylammonium bromide was dissolved in glycerol to obtain solution B. Solution B was added dropwise to solution A, mixed evenly, and then transferred to a high-pressure reactor. The mixture was reacted at 180°C for 16 h. After cooling, the mixture was washed and dried to obtain a black precursor.

[0011] S3, hydrolysis composite: The precursor was dispersed in deionized water, stirred at 50°C for 24 h, centrifuged, washed and dried to obtain Bi4O5Br2 / attapulgite composite photocatalyst.

[0012] Wherein, Bi4O5Br2 is a two-dimensional nanosheet structure and is uniformly coated on the surface of attapulgite, so that the mass ratio of attapulgite in the composite photocatalyst is 5wt% to 20wt%, forming a "sheet-rod" composite structure.

[0013] Further, in S1, attapulgite is heated to 400°C for 2 hours in air at a heating rate of 10°C / min, cooled to room temperature, and then mixed with 3 mol / L hydrochloric acid at a solid-liquid ratio of 1 g: 25 mL.

[0014] Furthermore, in S1, the mass ratio of Bi4O5Br2 to attapulgite is 80:20 to 95:5.

[0015] Furthermore, the attapulgite accounts for 15 wt% of the composite photocatalyst, resulting in a specific surface area of ​​85–95 m² for the composite material. 2 / g, with pore size distribution concentrated in 2-5nm.

[0016] Furthermore, in S2, the molar ratio of bismuth nitrate to hexadecyltrimethylammonium bromide is 2.55:1.

[0017] Furthermore, in S2, the ultrasonic treatment power is 300W, the frequency is 40kHz, and the solution temperature is less than 30℃ during the ultrasonic process.

[0018] Furthermore, in S2, the high-pressure reactor is filled to 80%, and after the reaction is completed, it is cooled to room temperature at a rate of 5°C / min.

[0019] Furthermore, the composite material has a light absorption threshold of 460–465 nm in the visible light region, corresponding to a band gap of 2.68–2.70 eV, and a photogenerated electron-hole pair recombination lifetime of 8.5–9.2 ns.

[0020] An application of a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst for the catalytic degradation of antibiotics in water under visible light, the antibiotics including ciprofloxacin and nitrofurantoin.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention employs a precise optimization of the attapulgite pretreatment process. Calcination can break the binding units between ATP structures, expose the rod-like features, and increase the specific surface area. Acid leaching reshapes the internal interconnected structure of silicate through etching, resulting in a completely exfoliated monodisperse rod-like structure. At the same time, this pretreatment process not only improves the adsorption performance of ATP (the dark adsorption rate of ciprofloxacin reaches 73%), but also provides abundant surface active sites for subsequent composite with Bi4O5Br2, solving the problems of insufficient natural ATP adsorption capacity and weak bonding with semiconductor composite interfaces.

[0023] 2. The design of this invention achieves the synergy of "adsorption-photocatalysis": the rod-shaped structure of ATP provides strong adsorption capacity, which can rapidly enrich antibiotics in water; the two-dimensional Bi4O5Br2 nanosheets provide a large number of photocatalytic active sites, and the interface between the sheet and the rod can promote the separation of photogenerated carriers (transient photocurrent test shows that the carrier separation ability of BOB / ATP-15 is significantly better than that of BOB or ATP alone).

[0024] 3. This invention achieves precise optimization of catalytic performance by controlling the composite ratio of attapulgite (5wt%~20wt%), breaking through the performance limitations of single materials. When the mass ratio of ATP is 15wt%, the effect of catalytic degradation of antibiotics in water under visible light is optimal. Moreover, the composite material has both the strong adsorption capacity of ATP and the high catalytic activity of Bi4O5Br2, solving the problems of high recombination rate of photogenerated carriers of single Bi4O5Br2 and the inability of single ATP to degrade. It realizes a continuous process of "rapid enrichment of pollutants - efficient mineralization".

[0025] 4. In this invention, under visible light excitation, valence band electrons of Bi4O5Br2 transition to the conduction band, and the conduction band electrons directly reduce the antibiotic or react with O2 to generate ·O2. - This enables the mineralization of pollutants; while the introduction of ATP inhibits electron-hole recombination through interfacial interactions (electrochemical impedance shows that its internal resistance is lower than that of ATP, and its photocurrent response is stronger), further improving catalytic efficiency. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall process of an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the XRD patterns of different ratios of BOB / ATP in embodiments of the present invention;

[0029] Figure 3 These are SEM images of attapulgite in various states according to embodiments of the present invention;

[0030] Figure 4 These are SEM images of the BOB under various states according to an embodiment of the present invention;

[0031] Figure 5 This is an elemental analysis diagram of BOB / ATP-15 according to an embodiment of the present invention;

[0032] Figure 6 These are XPS spectra of BOB and BOB / ATP-15 from embodiments of the present invention;

[0033] Figure 7 These are the UV-Vis absorption spectra of each component in an embodiment of the present invention;

[0034] Figure 8 This is a band structure diagram of the BOB according to an embodiment of the present invention;

[0035] Figure 9 These are photocurrent response diagrams of ATP, BOB, and BOB / ATP-15 according to embodiments of the present invention.

[0036] Figure 10 These are electrochemical impedance spectroscopy diagrams of ATP, BOB, and BOB / ATP-15 from embodiments of the present invention.

[0037] Figure 11 This is a graph showing the changes in the photocatalytic degradation curve of ciprofloxacin according to an embodiment of the present invention;

[0038] Figure 12 This is a cycle diagram showing the photocatalytic degradation effect of ciprofloxacin using BOB / ATP-15 according to an embodiment of the present invention;

[0039] Figure 13 This is a graph showing the experimental results of the influence of BOB / ATP-15 photocatalysis on ions in an embodiment of the present invention;

[0040] Figure 14This is a graph showing the changes in the photocatalytic degradation curve of nitrofurantoin according to an embodiment of the present invention;

[0041] Figure 15 This is a diagram showing the experimental results of BOB / ATP-15 photocatalytic free radical capture in an embodiment of the present invention;

[0042] Figure 16 This is a schematic diagram of the photocatalytic degradation mechanism of ciprofloxacin by BOB / ATP-15 according to an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figure 1 As shown in Example 1: This invention provides a method for preparing a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst (attapulgite mass percentage 15 wt%), comprising the following steps:

[0045] S1. Attapulgite Pretreatment: 2g of attapulgite (ATP) was placed in a ceramic crucible, covered, and placed in the center of a tube furnace. The temperature was increased to 400℃ at a rate of 10℃ / min, followed by heat treatment for 2 hours. (Calcination breaks down the binding units between ATP structures, exposing rod-like features and increasing specific surface area; acid leaching reshapes the internal interconnected structure of silicate through etching, resulting in a completely separated monodisperse rod-like structure while retaining the main ATP framework.) After cooling to room temperature, the calcined attapulgite was removed and ground to obtain calcined attapulgite, named ATP-S. The calcined attapulgite was added to a prepared 3mol / L HCl solution and stirred continuously for 3 hours. It was then centrifuged (8000r / min, 10min) and washed repeatedly until the pH was neutral (pH=7). Finally, it was dried in a 60℃ oven for 8 hours and ground into powder to obtain attapulgite that had undergone complete heat and acid treatment, named ATP-SS.

[0046] S2. Precursor Preparation: 80.7 mg (15 wt%) of calcined and acidified attapulgite was dispersed in 40 mL of glycerol and sonicated for 1 h (using 300 W power and 40 kHz frequency for 1 h, with the temperature controlled ≤30℃ during sonication) to obtain a uniformly dispersed attapulgite dispersion. This dispersion was placed in a 50℃ water bath, and 463.8 mg (1.275 mmol) of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) was added to obtain solution A. 136.5 mg (0.375 mmol) of hexadecyltrimethylammonium bromide (CTAB) was magnetically stirred and dissolved in 40 mL of glycerol for 30 min, then sonicated until completely dissolved, and this was designated solution B. Solution B was slowly added dropwise to solution A in a 50℃ water bath under continuous magnetic stirring (300 r / min) at a rate of 2 mL / min. The homogeneous suspension was then transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene (PTFE), heated to 180 °C and maintained for 16 h, and then allowed to cool naturally to room temperature. The composite precursor was obtained by washing with ethanol, centrifuging, and drying. The molar ratio of bismuth to bromine was controlled at 2.55:1. The resulting composite precursor was black in color and named BOB.

[0047] S3, hydrolysis composite:

[0048] The aforementioned composite precursor (0.5 g) was dispersed in 300 mL of deionized water at 50 °C and stirred for 24 h. During this process, the color of the suspension (bismuth-bromine ratio of 2.55:1) changed from black to light yellow. Subsequently, the hydrolysis product was washed three times with deionized water and ethanol, and dried to obtain a composite sample of Bi4O5Br2 and ATP. Bi4O5Br2 was named BOB, and the sample was named BOB / ATP. Furthermore, the content of attapulgite was investigated, and a Bi4O5Br2 / attapulgite composite photocatalyst (BOB / ATP-15) with an attapulgite mass ratio of 15 wt% was established.

[0049] Example 2:

[0050] A method for preparing a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst (attapulgite content 5 wt%).

[0051] Step S1 is the same as in Example 1;

[0052] In step S2, 26.9 mg (5 wt%) of acid-treated attapulgite and 618.4 mg (1.275 mmol) of bismuth nitrate pentahydrate were weighed and mixed to obtain solution A; at the same time, 182 mg (0.5 mmol) of hexadecyltrimethylammonium bromide (CTAB) was magnetically stirred and dissolved in 40 mL of glycerol for 30 min, and then sonicated until completely dissolved, which was recorded as solution B; the remaining operations were the same as in Example 1;

[0053] Step S3 is the same as in Example 1, resulting in a Bi3O5Br2 / attapulgite composite photocatalyst (BOB / ATP-5) with an attapulgite mass ratio of 5 wt%.

[0054] Example 3:

[0055] A method for preparing a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst (attapulgite content 10 wt%).

[0056] Step S1 is the same as in Example 1;

[0057] In step S2, 54.5 mg (10 wt%) of acid-treated attapulgite and 490.5 mg (1.006 mmol) of bismuth nitrate pentahydrate were weighed and mixed to obtain solution A; at the same time, 146.3 mg (0.398 mmol) of hexadecyltrimethylammonium bromide (CTAB) was dissolved in 40 mL of glycerol by magnetic stirring for 30 min, and then sonicated until completely dissolved, which was recorded as solution B; the remaining operations were the same as in Example 1;

[0058] Step S3 is the same as in Example 1, resulting in a Bi4O5Br2 / attapulgite composite photocatalyst (BOB / ATP-10) with an attapulgite mass ratio of 10 wt%.

[0059] Example 4:

[0060] A method for preparing a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst (attapulgite content 20 wt%).

[0061] Step S1 is the same as in Example 1;

[0062] In step S2, 107.6 mg (20 wt%) of acid-treated attapulgite and 430.4 mg (0.885 mmol) of bismuth nitrate pentahydrate were weighed and mixed to obtain solution A; at the same time, 126.7 mg (0.350 mmol) of hexadecyltrimethylammonium bromide (CTAB) was dissolved in 40 mL of glycerol by magnetic stirring for 30 min, and then sonicated until completely dissolved, which was recorded as solution B; the remaining operations were the same as in Example 1;

[0063] Step S3 is the same as in Example 1, resulting in a Bi4O5Br2 / attapulgite composite photocatalyst (BOB / ATP-20) with an attapulgite mass ratio of 20 wt%.

[0064] Phase analysis was performed on the nine prepared substances, and the results are as follows. Figure 2 As shown. From Figure 2As can be seen from the XRD patterns, ATP, ATP-S, and ATP-SS all exhibit the same characteristic diffraction peak at 26.5°, which belongs to the (011) crystal plane of SiO2 (JCPDS No.: 04-001-9367). The XRD pattern of BOB shows three characteristic diffraction peaks at 27.03°, 37.52°, and 39.48°, which belong to the (012), (104), and (110) crystal planes of Bi (JCPDS No.: 04-004-7365), respectively. The XRD patterns of BOB and different ratios of BOB / ATP show two identical characteristic diffraction peaks at 29.56° and 31.95°, which belong to the (411) and (020) crystal planes of Bi4O5Br2 (JCPDS No.: 01-071-3449), respectively.

[0065] Comparison of the XRD patterns of ATP, ATP-S, and ATP-SS shows that the characteristic diffraction peak at 26.5° of ATP remains after calcination and acid treatment, indicating that the main structure of ATP has not changed. Comparison of the XRD patterns of BOB, BOB, and different ratios of BOB / ATP shows that BOB, as a precursor of Bi4O5Br2, does not yet exhibit obvious characteristic diffraction peaks of Bi4O5Br2, while BOB and different ratios of BOB / ATP show obvious characteristic diffraction peaks of Bi4O5Br2, indicating that Bi4O5Br2 was successfully obtained after the precursor hydrolysis.

[0066] Morphological analysis of ATP, ATP-S, ATP-SS, BOB, BOB, and BOB / ATP-15 was performed using SEM, and the results are as follows: Figure 3 As shown in the image. Figure 3 (ab) are morphology diagrams of ATP at scale bars of 2μm and 200nm, respectively, showing that attapulgite is rod-shaped. Figure 3 (cd) are morphology diagrams of ATP-S with scale bars of 1 μm and 200 nm, respectively. It can be seen that the binding units between the attapulgite structures were released after calcination at 400℃ for 2 h, exposing the rod-shaped structural morphology. Figure 3 (ef) are morphology images of ATP-SS at scale bars of 1 μm and 200 nm, respectively. It can be seen that the internal correlation structure of the silicate ore was etched and reshaped after acid leaching with 3 mol / L hydrochloric acid for 3 h, resulting in a completely exfoliated monodisperse natural rod-shaped structure.

[0067] Figure 4 (ab) are scanning electron micrographs of BOB before hydrolysis at scale bars of 1 μm and 200 nm, respectively. It can be seen that BOB before hydrolysis exhibits an irregular blocky structure. Figure 4(c) is a morphology diagram of BOB with a scale bar of 2 μm. It can be seen that by hydrolyzing at 50 °C for 24 h, the blocky structure of BOB is transformed into a Bi4O5Br2 sheet structure. Figure 4 (d) is a morphology diagram of BOB / ATP-15 with a scale bar of 1 μm. It can be seen that BOB / ATP-15 prepared by solvothermal method contains both Bi4O5Br2 sheet structure and ATP rod structure, and BOB nanosheets are coated with ATP.

[0068] Elemental diffraction analysis of BOB / ATP-15 was performed by SEM. Figure 5 The results showed that the material contained Bi, Br, Si, and O elements, proving the successful preparation of the composite material.

[0069] X-ray photoelectron spectroscopy (XPS) was used to observe and analyze the surface elements and valence states of the catalyst samples. The binding energy obtained from the XPS analysis was calibrated with reference to C1s 284.6 eV. Figure 6 (a) shows that XPS scanning spectroscopy indicates that both the synthesized BOB and BOB / ATP-15 samples contain Bi, O, and Br elements, and BOB / ATP-15 also contains Si, indicating successful synthesis. High-resolution XPS spectroscopy was used to confirm the chemical state of the samples, see [link to relevant documentation]. Figure 6 (bd). For example... Figure 6 As shown in (b), the peaks at 158.73 eV and 158.53 eV are characteristic peaks of Bi 4f in BOB and BOB / ATP-15, indicating the presence of Bi in the sample. 3+ . Figure 6 In (c), the peaks at 68.18 eV and 68.07 eV are characteristic peaks of Br3d in BOB and BOB / ATP-15, indicating the presence of Br in the sample. - . Figure 6 In (d), the peaks at 529.93 eV and 531.32 eV are characteristic O1s peaks of BOB and BOB / ATP-15, indicating the presence of O in the sample. 2- .

[0070] UV-Vis absorption spectroscopy analysis was performed on ATP, ATP-S, ATP-SS, BOB, BOB, BOB / ATP-5, BOB / ATP-10, BOB / ATP-15, and BOB / ATP-20. The results are as follows: Figure 7 (a) As ATP is loaded onto BOB at different ratios, the absorption intensity in the visible light region significantly increases, thus enhancing the response range of the composite material in the visible light region. The UV-Vis absorbance spectra of BOB were processed according to formula (1-1):

[0071] αhv=A(hv-Eg) n / 2 (1-1) Bi4O5Br2 is an indirect bandgap semiconductor, with n taking the value of 4. For example... Figure 7 As shown in (b), the Eg corresponding to BOB is 2.68eV, calculated according to formula (3-1).

[0072] BOB's Mott-Schottky test was performed at frequencies of 100Hz, 200Hz, and 300Hz, and the results are as follows: Figure 7 As shown. From Figure 7 As shown in (c), the Fermi level of the BOB sample is approximately -0.90 V. According to formula (1-2):

[0073] E CB =E θ CB +0.197V (1-2)

[0074] The calculated ECB of BOB is -0.703V. Based on the previous solid-state UV experiments, the Eg of BOB is 2.68eV. Using formula (1-3):

[0075] E g =E VB -E CB (1-3)

[0076] The calculated valence band (EVB) of the BOB is 1.977V, which is consistent with... Figure 7 (d) shows that the valence band of the BOB, as measured by X-ray photoelectron spectroscopy, is close to 1.90 eV. Based on the above data, the schematic diagram of the band structure of the BOB is as follows. Figure 8 As shown.

[0077] Transient photocurrent response performance of three materials, ATP, BOB, and BOB / ATP-15, was tested. Figure 9 As shown in the figure, the current density of the three curves fluctuates during the first 100 seconds, indicating that the generation and recombination of photogenerated carriers are unstable. After 100 seconds, the overall trend stabilizes. It can be seen that the BOB / ATP-15 sample exhibits the strongest transient photocurrent response, indicating that the BOB / ATP-15 sample has better separation and transport capabilities for photogenerated electrons and holes. This suggests that the recombination of BOB and ATP helps enhance the separation of photogenerated carriers, which is beneficial for improving catalytic activity.

[0078] Electrochemical impedance spectroscopy was performed on the three samples: ATP, BOB, and BOB / ATP-15. The results are as follows: Figure 10As shown in the figure, k(BOB) > k(BOB / ATP-15) > k(ATP). The electrochemical impedance spectroscopy curve for BOB has the steepest slope, indicating that BOB has the lowest internal resistance. The slope of the BOB / ATP-15 electrochemical impedance spectroscopy curve falls between that of ATP and BOB, and the slopes of all three are close, indicating that the recombination of BOB and ATP still maintains a relatively low internal resistance, which is beneficial for carrier transport at the interface.

[0079] The following is about the photocatalytic degradation of ciprofloxacin using a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst:

[0080] Under visible light irradiation, the photocatalytic degradation performance of ATP, BOB, BOB, and different ratios of BOB / ATP catalysts was evaluated by degrading 20 mg / L ciprofloxacin. The results are as follows: Figure 11 As shown in (a), ATP exhibits certain dark adsorption capacity for ciprofloxacin; after 1 hour of dark treatment, 73% of the ciprofloxacin was adsorbed. BOB shows good photocatalytic degradation of ciprofloxacin; after 2 hours of light exposure, 99.6% of the ciprofloxacin was degraded. Different ratios of BOB / ATP combine the dark adsorption capacity of ATP with the photocatalytic degradation capacity of BOB, with BOB / ATP-15 showing the best performance and a degradation rate as high as 98.6%. Figure 11 As can be seen in (b), the intensity of the characteristic peak of ciprofloxacin continuously weakens over time, indicating that ciprofloxacin is continuously mineralized and decomposed into small molecules under the action of catalysis.

[0081] In addition, five repeated cyclic catalytic experiments were conducted on the BOB / ATP-15 catalyst, and the results are as follows: Figure 12 As shown in the figure. After a 1-hour dark treatment, followed by a 2-hour light irradiation, the catalyst was washed, dried, and recovered for use in the next cycle. This process was repeated five times. In the fifth experiment, compared to the first experiment, the degradation rate decreased from 97.5% to 87.3% after 2 hours of light irradiation, representing a 10% decrease in catalytic efficiency. After five cycles, BOB / ATP-15 still exhibited high catalytic activity, with a degradation performance of over 85% for ciprofloxacin, indicating that BOB / ATP-15 possesses good cycle stability.

[0082] In practical photocatalytic water treatment, due to the presence of a large number of inorganic salt ions in the water, the influence of multiple ion factors in the water body needs to be investigated, such as... Figure 13 .from Figure 13 As shown in (a), the addition of cations has a certain impact, resulting in a slight decrease in absorbance during the adsorption stage. Furthermore, the addition of cations promotes catalysis during the adsorption stage, but the final performance remains similar, with all achieving a degradation rate of 97.2%. This indicates that K... + Na+ Mg 2+ The effect of BOB / ATP-15 on the degradation of ciprofloxacin is relatively weak.

[0083] from Figure 13 As shown in (b), the addition of anions has a certain impact, resulting in a slight decrease in absorbance during the adsorption stage. Furthermore, the addition of anions promotes catalysis during the adsorption stage, but the final performance remains similar, with all achieving a degradation rate of 96.7%. This indicates that Cl... - NO3 - The effect of BOB / ATP-15 on the degradation of ciprofloxacin is relatively weak.

[0084] The following is about the photocatalytic degradation of furazolidone using a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst:

[0085] Nitrofurantoin, also an antibiotic like ciprofloxacin, is widely used to evaluate the photocatalytic performance of prepared samples. Under visible light irradiation, the photocatalytic degradation performance of ATP, BOB, BOB, and different BOB / ATP ratios was evaluated by degrading 20 mg / L nitrofurantoin. The results are as follows: Figure 14 As shown in (a), BOB exhibits good photocatalytic degradation of nitrofurantoin, degrading 94.5% of the nitrofurantoin after 2 hours of illumination. ATP, however, shows poor adsorption of nitrofurantoin, with only 52.2% adsorbed after 3 hours. Nevertheless, different ratios of BOB / ATP still retain the photocatalytic degradation ability of BOB, with BOB / ATP-15 showing the best performance, achieving an 89.6% degradation rate of nitrofurantoin after 2 hours of illumination. Figure 14 As can be seen in (b), the intensity of the characteristic peak of nitrofurantoin continuously weakens over time, indicating that nitrofurantoin is continuously mineralized and decomposed into small molecules under the action of catalysis.

[0086] In the catalytic degradation of ciprofloxacin and nitrofurantoin, there are generally holes (h + ), electron (e - ), superoxide radicals (·O2) - The generation of reactive species such as hydroxyl radicals (·OH) can affect catalytic degradation. Therefore, the catalytic mechanism of the catalyst was investigated by adding specific reagents to capture the corresponding free radicals. Among the prepared catalysts, BOB / ATP-15 showed the best overall performance. Free radical capture experiments were conducted using BOB / ATP-15, with ciprofloxacin, which showed better degradation performance, as the pollutant for degradation.

[0087] Nitrogen, isopropanol, silver nitrate (AgNO3), and ammonium formate (AF) can be used to capture ·O2. - ·OH, e- and h + .Depend on Figure 15 It can be seen that the degradation rate of ciprofloxacin by BOB / ATP-15 is increased to some extent under the action of ammonium formate and isopropanol. The promoting effect of ammonium formate may be due to the reduction of holes, which improves the separation and transport efficiency of photogenerated electrons and holes, indicating that h + It is not a key catalytically active species. The promoting effect of isopropanol may be because isopropanol captures ·OH, forming an isopropoxy radical, which can directly react with ciprofloxacin molecules, causing ciprofloxacin to decompose. This indicates that ·OH is not a key catalytically active species either. Simultaneously, purging with nitrogen gas has a weak inhibitory effect on the catalytic activity of the system, indicating that ·O2... - It is a secondary catalytically active species. The degradation rate of ciprofloxacin was significantly slowed down under the action of silver nitrate, indicating that under visible light irradiation, BOB / ATP-15 exhibits secondary catalytic activity towards the ciprofloxacin catalytically active species. - The main factor is... The results show that the relative effects of the catalytically active species are: e... - O2 - .

[0088] Based on this, the catalytic mechanism of BOB / ATP-15 photocatalytic degradation of ciprofloxacin was explored. For example... Figure 16 As shown, during the degradation of ciprofloxacin, the material is excited under visible light irradiation, causing electrons in the valence band to transition to the conduction band, forming electron-hole pairs. The electrons in the conduction band possess a certain reducing ability and can directly react with ciprofloxacin, degrading it into H2O and CO2. Simultaneously, the electrons can react with oxygen molecules in the environment to generate superoxide radicals (·O2). - It has high reactivity and can further react with ciprofloxacin molecules, accelerating the degradation of ciprofloxacin.

[0089] In summary, through synergistic innovation in pretreatment process optimization, composite structure design, performance regulation, and mechanism revelation, a highly efficient coupling of "adsorption-photocatalysis" has been achieved, providing a new paradigm for the functionalization of natural silicates and bismuth-based semiconductors, and also offering a high-performance, highly stable photocatalytic material solution for the treatment of new antibiotic pollutants.

[0090] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst, characterized in that, The method comprises the following steps: S1, pre-treatment of palygorskite: calcining palygorskite at 400℃ for 2h, stirring with 3mol / L HCl solution for 3h after grinding, washing by centrifugation until neutral, drying at 60℃ for 8h, to obtain acid-treated palygorskite; S2, preparation of precursor: dispersing the acid-treated palygorskite in glycerol, ultrasonic treatment for 1h, adding bismuth nitrate pentahydrate, to obtain solution A; dissolving cetyltrimethylammonium bromide in glycerol to obtain solution B; adding solution B dropwise into solution A, uniformly mixing, and then transferring into a high-pressure reaction kettle, reacting at 180℃ for 16h, washing and drying after cooling, to obtain a black precursor; S3, hydrolysis and compounding: dispersing the precursor in deionized water, stirring at 50℃ for 24h, washing by centrifugation and drying, to obtain a Bi4O5Br2 / palygorskite composite photocatalyst; wherein: the Bi4O5Br2 is a two-dimensional nanosheet structure, and uniformly coats the surface of the palygorskite, so that the mass ratio of the palygorskite in the composite photocatalyst is 5wt%-20wt%, forming a "sheet-rod" composite structure.

2. The preparation method of the two-dimensional Bi4O5Br2 composite attapulgite photocatalyst according to claim 1, characterized in that, In the S1, the palygorskite is calcined at 400℃ for 2h under air atmosphere at a heating rate of 10℃ / min, and after cooling to room temperature, 3mol / L hydrochloric acid is added at a solid-liquid ratio of 1g:25mL.

3. The preparation method of the two-dimensional Bi4O5Br2 composite attapulgite photocatalyst according to claim 1, characterized in that, In the S1, the mass ratio of Bi4O5Br2 to palygorskite is 80:20-95:

5.

4. The preparation method of the two-dimensional Bi4O5Br2 composite attapulgite photocatalyst according to claim 3, characterized in that, The mass ratio of the attapulgite in the composite photocatalyst is 15wt%, so that the specific surface area of the composite material is 85-95m 2 / g, and the pore size distribution is concentrated in 2-5nm.

5. The preparation method of the two-dimensional Bi4O5Br2 composite attapulgite photocatalyst according to claim 1, characterized in that, In the S2, the molar ratio of bismuth nitrate to cetyltrimethylammonium bromide is 2.55:

1.

6. The preparation method of the two-dimensional Bi4O5Br2 composite attapulgite photocatalyst according to claim 1, characterized in that, In the S2, the power of ultrasonic treatment is 300W, the frequency is 40kHz, and the solution temperature during ultrasonic treatment is less than 30℃.

7. The preparation method of the two-dimensional Bi4O5Br2 composite attapulgite photocatalyst according to claim 1, characterized in that, In the S2, the filling degree of the high-pressure reaction kettle is 80%, and after the reaction is completed, the temperature is lowered to room temperature at a rate of 5℃ / min.

8. The method for preparing the two-dimensional Bi4O5Br2 composite attapulgite photocatalyst according to claim 1, characterized in that, The light absorption threshold of the composite material in the visible light region is 460-465nm, the corresponding band gap is 2.68-2.70eV, and the photoelectron-hole pair recombination lifetime is 8.5-9.2ns.

9. Use of a two-dimensional Bi4O5Br2 composite attapulgite photocatalyst, characterized in that, The method is used for catalytic degradation of antibiotics in water under visible light, and the antibiotics include ciprofloxacin and furantoin.

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